Glossary – A

ACK & PUSH ACK Flood

After a TCP-SYN session is established between a host and a client, ACK or PUSH ACK packets are used to communicate information back and forth between the two until the session is closed. During an ACK flood, a victim receives spoofed ACK packets at a high packet rate that fail to belong to any session within the server’s connection list. The ACK flood exhausts a victim’s server by depleting its system resources (memory, CPU, etc.) used to match these incoming packets, resulting in performance degradation or a complete server shutdown.